Piezoelectric oscillator



March 26', '1940. w. SCHNEIDER 2,194,675

PIEZQELECTRIC OSCILLATOR Filed March 16, 1938 2 I 3 MefalllBecZ JZw/oc v INVENTOR W/LHELM SGHNE/DER ATTORNEY Patented Mar. 26, 1940 PIEZOELECTRIC OSCILLATOR Wilhelm Schneider, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b. 11., Berlin, Germany, a corporation of Germany Application March 16, 1938, Serial No. 196,095 In Germany February 26, 1937 13 Claims.

The present invention is concerned with means to hold or support piezoelectric oscillator crystals, especially bar or rod-shaped oscillators which are excited so as to undergo longitudinal vibrations.

An object of this invention is to simplify and improve crystal holders generally;

Another object of this invention is to provide a novel method of centrally supporting a piezoelectric crystal by pins located at right angles to each surface of the crystal.

It is known in the prior art to support such oscillable bodies in the nodal point of the oscillation between points or balls which are arranged at both ends or sides of the crystal and. which are subjected to pressure in reference to each other. However, holder devices of this kind involve the drawback that the crystal is liable to be twisted and may thus come into contact with objects located in the neighborhood, and this would mean a disturbance to the production of oscillation.

According to the invention the crystal which is metallized upon its surface is provided in its vibration nodal point with bolts or pins positioned at right angles to the surface of the crystal, said pins or bolts being fixedly clamped in a holder device.

Several exemplified embodiments of the invention are illustrated in the drawing, in which:

Fig. 1 is a plan view of a crystal and support pins;

Fig. 2 is a side elevation of the crystal of Fig. l and the side uprights;

Fig. 3 is a perspective view of the crystal holder; and

Fig. 4 is a partial sectional view with the supporting pins cut out of the crystal.

Referring to Fig. l, i denotes the crystal, 2 is the metallization, and 3 and 4 denote two bolts or pins. The latter are metallized, this metallized coat being connected with the conducting surface layer of the crystal so that these pins or bolts may serve at the same time as voltage leads. The material of which the pins are made consists preferably of insulation, say, glass or ceramic, having a low coefiicient of expansion, and they are provided with a superficial metallized cost. However, instead of that also bolts or pins of metal, say, steel, may be used. These pins may be cemented fast upon the surfaces of the crystal or else the crystal is drilled all the way through at a nodal point of its vibration so that a single continuous pin may be employed which is firmly cemented into the bore.

Fig. 2 is a lateral view of the crystal and its holder means. i again denotes the crystal, I2 is a support or pedestal preferably made of metal having at its top end a bearing l3 adapted to be clamped fast and into which the holder pins of the crystal extend. The clamping of the bearing or support is preferably effected, as shown, in such a way that the bearing is split and is provided with a clamp screw l0. However, instead of this device recourse could be had also to other ways and means designed to insure the holder pins of the crystal being firmly held in clamped position.

Fig. 3 is a perspective view of the entire holder assembly. 2 is the crystal, 3 and t the holder pins, l2 and M are the bearing supports or up- 1 rights secured to a base l5. Since uprights l2 and l-i consist of metal they could suitably serve at the same time for the voltage leads; in other words, connection with the crystal is effected directly at these two bearings or supports, so that no further electrode arrangements are required. A preferable embodiment results if to each of the two pedestals or uprights a plug it is directly attached so that the whole assembly comprising the crystal and the holder means may be plugged into sockets and may be readily replaced.

In the figures of the'drawing, is illustrated a longitudinally oscillating crystal rod which is centrally supported. However, it will be understood that the present innovation is not restricted to this merely illustrative embodiment, in fact, it will be found useful also for other forms of crystal. It is also possible to cut or mill the supporting or holder pins conjointly with the crystal out of one mother crystal so that there is no need for drilling holes or cementing as illustrated by Fig. 4. Finally, it is also possible to accommodate the arrangement as described inside a shielding case made, if desired, of metal.

What is claimed is:

l. Holder means especially adapted to rodshapeol piezoelectric crystals with the characteristic feature that the crystal having metallized surfaces, at its nodal point of vibration is provided on both sides with electrically conducting pins positioned at right angles to the crystal surfaces, said pins being firmly clamped in a clamping device and serving at the same time as supply leads for the crystal.

2. Holder as claimed in claim 1, with the characteristic feature that the crystal has a throughdrill-hole and that in this hole is fitted a pin or bolt protruding at both ends with the latter metallized, the pin consisting of insulation material.

3. Holder as claimed in claim 1, with the characteristic feature that the pin is secured by cementing.

4. Holder as claimed in claim 1, with the characteristic feature that the pin or pins consist 5 of metallized glass or metallized ceramic material.

5. Holder as claimed in claim 1, with the char acteristic feature that the pins are integral with said crystal.

6. I-Iolder as claimed in claim 1, with the characteristic feature that the pins are secured in bearing pedestals adapted to be clamped.

7. A piezoelectric crystal plate, a metallic mem ber securely cemented directly to and at right angles to both faces of said crystal plate, and a metallized coat covering both faces of said crystal plate.

8. A piezoelestric crystal plate, a metallic rodlike member securely cemented directly to and. at right angles to both faces of said crystal plate,

and a metallized coat covering the cement and both faces of said crystal plate, said metallized coat being in electrical contact with said rod-like member.

9. A piezoelectric crystal plate, a metallic terminal member securely cemented directly to and at right angles to both faces of said crystal plate, and a metallized coat covering both faces of said crystal plate.

10. The method of making electrical connection to a piezoelectric crystal plate mounted at its nodal point, including the steps of applying a cement to both faces of said crystal plate at its nodal point, attaching a support member to said crystal by said cement, and coating both faces and support member with a metal coating so that said metal surrounds said support member and covers said cement.

11. The method of producing a piezoelectric crystal which included the steps of applying cement to the nodal point of vibration of said crystal, attaching a terminal member to said crystal by said cement, and applying a metal coat over said crystal face, cement and terminal member.

12. A crystal holder for a piezoelectric crystal having a metallized surface comprising a pin located at right angles and secured to each crystal surface and at its nodal point of vibration, said pins being clamped in a clamping device having two uprights of metal which serve as electric terminals for said crystal holder.

13. A crystal holder for a piezoelectric crystal having a metallized surface comprising a pin located at right angles and secured to each crystal surface and at its nodal point of vibration, said pins being clamped in a clamping device having two uprights of metal, and a pin located in the lower portion of said uprights for fitting into sockets which serve as electric terminals for said holder.

WILI-IELM SCHNEIDER. 

